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From: Ingo Oeser <ioe-lkml@rameria.de>
To: linux-kernel@vger.kernel.org
Subject: Re: large files unnecessary trashing filesystem cache?
Date: Wed, 19 Oct 2005 17:54:11 +0200
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Cc: gfiala@s.netic.de
References: <200510182201.11241.gfiala@s.netic.de> <20051018213721.236b2107.akpm@osdl.org> <1129720232.435629a8753d3@webmail.LF.net>
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Hi,

On Wednesday 19 October 2005 13:10, gfiala@s.netic.de wrote:
> Zitat von Andrew Morton <akpm@osdl.org>:
> > So I'd also suggest a new resource limit which, if set, is copied into =
the
> > applications's file_structs on open().  So you then write a little wrap=
per
> > app which does setrlimit()+exec():
> >=20
> > 	limit-cache-usage -s 1000 my-fave-backup-program <args>
> >=20
> > Which will cause every file which my-fave-backup-program reads or write=
s to
> > be limited to a maximum pagecache residency of 1000 kbytes.
>=20
> Or make it another 'ulimit' parameter...

Which is already there: There is an ulimit for "maximum RSS",=20
which is at least a superset of "maximum pagecache residency".

This is already settable and known by many admins. But AFAIR it is not
honoured by the kernel completely, right?

But per file is a much better choice, since this would allow
concurrent streaming. This is needed to implement timeshifting at least[1].

So either I miss something or this is no proper solution yet.


Regards

Ingo Oeser

[1] Which is obviously done by some kind of on-disk FIFO.


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